Preparing the Fruit:

Boil 5-6 inches of water in a large pot. Place the peaches in it and let them boil for 1 minute. Remove them to a bowl of ice water.

Peel and slice the peaches into a large bowl. Add the lemon juice and toss them. 

Stir in the blueberries, sugar, and salt. Set the bowl of fruit aside.

Preparing the Cobbler Topping:

Preheat the oven to 350°. Place 8 Tbsp. of butter in an 8×8 pan (or any pan that holds about 8 cups-see recipe notes above). Put the pan in the oven until the butter has melted. Swirl the butter to cover the bottom and edges of the pan.

In a mixing bowl, whisk together the flour, sugar, baking powder, salt, and vanilla. Add the milk and pour in the melted butter from the pan and stir until the mixture is well combined.

Place the fruit in the buttered pan. Pour the cobbler batter (it should be about the consistency of cake  batter) over the blueberries and peaches.

Sprinkle the top of the cobbler with 3-4 Tbsp. of sugar.

Bake the cobbler for 45-50 minutes, or until the top is golden brown.

Remove the cobbler from the oven and let it cool. You can serve it warm or cold, and with or without ice cream.

Store any leftover blueberry peach cobbler in the refrigerator.